Study On A New Technology Of Refractory Scheelite Flotation At Room Temperature

Seperation of scheelite from fluorite and calcite has been a difficulty research program in the mineral processing field all over the world. Petrov Method is the traditional way for scheelite flotation, during which high quantity of water glass is added to the high concentrate slurry of scheelite in the higher alkalinity condition with long time continual stirring at 90℃. It has been considered as a adverse processing method, according to its high energy cost, high expense and adverse working environment. All these conditions call for a new technic which can put the scheelite normal temprature flotation into reality.This paper investigated the scheelite normal temprature flotation through flotation experiments and mechanism research. The main results are showed as follows:Single mineral tests indicated that:With CaO+Na2CO3,Na2CO3,NaOH as the PH modifiers separately and water glass as the depresant, the flotability differences between scheelite, fluorite and calcite were big and best; while with Na2CO3 the differences were worst. During the flotation of scheelite from scheelite-fluorite ore with those modifiers discussed above, water glass had brilliant selective depression effect on fluorite, achieving scheelite precedence flotation; while in the flotation scheelite from scheelite-fluorite-calcite ore, lime method showed the best result.Actual flotation tests results showed that:733 oxidized paraffin soap and benzyl hydroxamic acid (ratio 10:1) was proved to be an excellent collector as it had outstanding collectibility and selectivity; With lime method in laboratory closed circuit experiment, the concentration of rough concentrate scheelite (WO3) reached 3.25% with recovery of 76.08%. At normal tempratur with lime method in open circuit process, the concentration of concentrate scheelite (WO3) of 37.8%, recovery of 38.74% and the enrichment ration was as high as 100. It was proved by the XRD analyse that with lime method most of the fluorite was well depressed in the coughing flotation period, and calcite was well depressedin at the cleaning period. In conclusion, as the replacement of the Petrov method, the lime method actualized the seperation of scheelite from calcium-bearing Gangue minerals at normal temprature.Mechanism investation showed that:in the higher alkalinity condition, the surfaces of scheelite, fluorite and calcite wore negative charge, so the collector reacted with these three minerals through the dissolved Ca2+ on its surface, accordingly resulted the similar flotability. On the other side, by adding lime, fluorite and calcite could charged high positive charge since it absorbed big amount of Ca2+,while the scheelite remained negative charge. After adding Na2CO3, the Zata potial of the surface of the fluorite and calcite changed to negative obviously, while the scheelite did not change too much, and this trend increased by adding water glass continously, which indicated that the absorption amount of water glass on the surface of fluorite and calcite was much higher than that of the scheelite, and this was also improved by the solvent chemistry investigation and absorption amount experiments.